1. Field of the Invention
The present invention relates to a heat removal system, and particularly to a heat removal system incorporating an angled fan and a system fan for cooperatively enhancing the efficiency of heat dissipation.
2. Related Art
Developments in today""s highly information-intensive society have led to remarkable improvements in performances of electronic devices. Large amounts of heat are produced during operation of electronic devices such as CPUs. The heat must be quickly removed to prevent the system from becoming unstable or being damaged. Typically, a heat sink is attached to an outer surface of the electronic device to facilitate removal of heat therefrom. A fan is often attached to the heat sink to provide forced convection.
A conventional heat removal system is shown in FIG. 3. A horizontal fan 2 is mounted to fins of a heat sink, to force air to flow between the fins and toward a base of the heat sink. A system fan 5 is attached to a rear panel 4 of a computer enclosure 3. The horizontal fan 2 creates vertical forced convection, and the system fan 5 creates horizontal forced convection. However, portions of the vertical forced airflow rebound from the base of the heat sink, and the horizontal forced airflow interferes with portions of such rebounded airflow. Thus the overall efficiency of forced convection is reduced.
FIG. 4 shows another kind of conventional heat removal system, wherein a vertical fan 2xe2x80x2 is attached to a side of a heat sink 6xe2x80x2. The fan 2xe2x80x2 forces air to pass horizontally between fins 7xe2x80x2 of the heat sink 6xe2x80x2 in directions generally parallel to a base of the heat sink 6xe2x80x2. The hottest part of the heat sink 6xe2x80x2 is the base, which is in thermal contact with a CPU. Airflow nearest the base is able to effect significant heat removal therefrom. However, other airflow farther away from the base always remains too far away from the base to effect significant heat removal therefrom. Furthermore, air adjacent the base is hottest, and tends to rise therefrom. Such. rising air tends to push the horizontal airflow upwardly and away from the base, thereby further reducing the efficiency of heat removal from the base.
Thus, a heat removal system which optimizes the efficiency of forced convection is desired.
Accordingly, an object of the present invention is to provide a heat removal system which dissipates heat efficiently.
Another object of the present invention is to provide a heat removal system having improved forced convention.
To achieve the above-mentioned objects, a heat removal system comprises a heat dissipation assembly and a system fan which cooperatively achieve optimized heat dissipation efficiency. The heat dissipation assembly comprises a heat sink and an angled fan. The heat sink comprises a base and a plurality of parallel fins. A slanted surface is defined by a set of adjacent edges of the fins. The fan defines a through hole at each of four corners thereof. Four screws extend through the through holes, thus attaching the fan to the heat sink at the slanted surface. A rotational axis of the fan intersects a central portion of the base of the heat sink, which portion defines a region of highest temperature of the heat sink. The angled fan together with the system fan provide maximized cooling airflow.